1. Field of the Invention
The present invention relates to a coaxial electric connector configured so that cylindrical contacts are mutually mated/removed.
2. Description of the Related Art
Generally, in various electric devices, etc., electric connectors for electrically connecting various signal transmitting media such as coaxial cables are widely used. For example, in a coaxial electric connector shown in FIG. 9, a plug connector 2 to which a terminal part of a coaxial cable serving as a signal transmitting medium (see a symbol SC in FIG. 2 showing the present invention) is coupled is configured to be able to be mated/removed in the top-bottom direction of the drawing with respect to a receptacle connector 1 mounted and used on a printed wiring board. Among them, in the receptacle connector 1, a center contact 1b for signal transmission and an external contact 1c for grounding are approximately-concentrically attached to a plate-like insulating housing 1a. An insulating housing 2a of the plug connector 2 is formed so as to approximately conically project toward the above described coaxial receptacle connector 1, and a center contact 2b for signal transmission and an external contact 2c for grounding are approximately concentrically attached to the inside/outside of the insulating housing 2a. 
Then, when the plug connector 2 serving as the opposing connector is inserted to the receptacle connector 1 downward from the upper side, the distal-end opening part of the external contact 2c of the plug connector 2 is configured to be mated with the distal-end opening part of the external contact 1c of the receptacle connector 1 so that the parts are overlapped in the inside/outside of the radial direction and locked. More specifically, among the both external contacts 1c and 2c mated in the above described manner, a lock part 1d forming an annular recessed shape recessed toward the inner side of the radial direction is provided on the outer peripheral surface of the inner-side contact 1c positioned in the inner side of the radial direction, and a lock part 2d having an annular projected shape projecting toward the inner side of the radial direction is provided on the inner peripheral surface of the outer-side conductive contact 2c positioned in the outer side of the radial direction. When the above described both connectors 1 and 2 are mated with each other, the lock part 2d of the coaxial plug connector 2 side is dropped into the lock part 1d of the coaxial receptacle connector 1 side to achieve an engaged state so that the mutual mating state of both of the connectors 1 and 2 can be maintained.
On the other hand, downsizing and height reduction have been recently rapidly developed along with demands for reducing weight, thickness, and size also in such a coaxial electric connector as well as other electronic parts. However, when downsizing and height-reduction are carried out, the alignment upon mating mutually between both the connectors becomes difficult. For example, as shown in FIG. 10, the plug connector 2 serving as the opposing connector is mated with the receptacle connector 1 in an state in which the plug connector 2 is inclined, which may cause damage or a problem in the electric contact performance mutually between both of the connectors 1 and 2.
Furthermore, in the conventional coaxial electric connector, when both of the connectors are to be mated with each other, the inner peripheral surface of the outer-side contact becomes a lightly-press-fitted state with respect to the inner-side contact. Therefore, the outer-side contact is inserted so as to be pushed and expanded toward the outer side of the radial direction. However, in that process, contact mutually between the center contacts of both of the connectors is started approximately at the same time. Therefore, there are problems that load in the mating operation is increased, and the position or the balance of the electric connector in the mating operation easily becomes defective.